Extended Response

The fossil record of echinoderms dates to the Cambrian period, more than 500 million years ago. Scientists have observed many well-preserved echin-oderm species from this period.

Part A Based on the fossil evidence, which characteristics did the earliest adult echinoderms have, in terms of symmetry and ability to move?

Part B Based on your answer to Part A, describe the evolution of echinoderms.

If you are unsure of the answers to particular questions, put a mark beside them (on your answer sheet or test booklet), and go on to other questions. If you have time, go back and reconsider the questions you skipped. (Do not write in this book.)

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